1. Field of the Invention
The present invention relates to a film formation method for forming an organic compound layer of an organic electroluminescent device or the like by vapor deposited.
2. Description of the Related Art
An organic electroluminescent device has attracted attention as a display device adaptable to a full-color flat panel display. The organic electroluminescent device is a self-luminous type device which emits light by electrically exciting an organic compound layer having fluorescence or phosphorescence, and is a thin-type device capable of performing multicolor emission with a high luminance and a large viewing angle at plane emission. The organic electroluminescent device exhibits a desired function by stacking a plurality of thin films each having a thickness of the order of nanometer. In flat panel display in which such organic electroluminescent devices are arrayed in a substrate surface, it is an important problem in production of the device to make the film thickness distribution of a plurality of thin organic compound layers constituting the devices uniform.
As a vapor deposition apparatus for producing such an organic electroluminescent device, a vapor deposition apparatus disclosed in Japanese Patent Application Laid-Open No. 2004-35964 will be simply described.
The vapor deposition apparatus is configured to fix a substrate on a fixing part in a vacuum chamber, and to perform vapor deposition while moving a vapor deposition source by a vapor deposition source movement mechanism to a plurality of different directions of X, Y, Z or θ, or to a synthesized direction of the plurality of the directions.
The vapor deposition apparatus in which a distance between the vapor deposition source and the substrate is shortened and the deposition source is moved along the substrate surface enables uniform in-plane thickness distribution of a formed thin film and improvement of the efficiency of a vapor deposition material by reducing the wastefully scattered amount of the vapor deposition material outside the substrate.
However, with the conventional technology disclosed in Japanese Patent Application Laid-Open No. 2004-35964, when a multiple-panel forming process in which a plurality of panels is produced on a large-size substrate is employed, when production of the device is continued over a long period of time or in other cases, a constant film thickness distribution is difficulty obtained and the yield is also reduced. Hence, a display device provided with the organic electroluminescent device has such a problem that light emission unevenness in pixels and substrate surfaces occur and luminance deterioration is accelerated due to too much electric current in regions having an insufficient thickness.